An electrolysis cell for the electrolytic separation of metals out of a liquid containing metal ions is known from German Patent DE-PS 36 40 020, and U.S. Pat. No. 4,786,384, GERHARD et al., which has, in a trough, at least one anode and a plurality of flat cathodes disposed parallel level to each other and at a distance from each other, which are each connected by means of their own connectors with the power supply via connecting resistances of various sizes.
The electrode plates used as cathodes are individually arranged in the trough and have sufficient stability; they can also be swapped out individually. Due to the wall thicknesses required for the stability of the individual cathodes, there is a comparatively high loss of material in the course of each change or swap of the cathodes when it occurs.
An electrolysis cell is also known from U.S. Pat. No. 3,788,965, HOLISINGER where an anode plate with a plurality of cathode plates disposed at a distance from each other, but where only the cathode plate which is farthest away from the anode is connected with the negative potential of the power supply. The cathode plates have openings for a zig-zag-shaped ion flow, in the course of which copper from the solutions containing copper ions is deposited on the plates themselves. Following deposition of copper, the cathode plates are swapped out and replaced by non-plated cathode plates.
According to the U.S. Patent, a certain mimimum wall strength of the electrode plates, used as cathode plates, is also required because they must be individually swapped out, which also results in high material losses upon every swap-out.
Further, German patent disclosure 2 213 401 (A), JACCAUD, discloses an electrolysis apparatus for silver recovery from an upstream photographic fixing bath, in which the cathode plates are fastened on a common carrier, parallel to each other with interposed spacer rings, and are suspended as a cathode packet on a housing wall of the apparatus. The anodes, which are rod-shaped with circular cross-section, are arranged along the housing wall in a plane which runs perpendicular to the plane of the individual cathode plates.
Problematical, in this connection, is the relatively great requirement for anode material, since the service life of the anodes is limited and, due to the multiplicity of anodes, extensive/expensive swapping out is necessary.
Proceeding from German Letters Patent DE-PS 36 40 020, GERHARDT et al., it is the object of the invention to provide material-saving cathode systems with large cathode surfaces, with which it is possible to achieve high current efficiency in spite of low material and production costs. In addition, it is also intended to obtain easy handling during operation.
In a preferred embodiment, the support device consists of four rods guided through recesses in the electrode plates, where spacer elements are disposed between the electrode plates, and the respectively outside electrode plates are pressed together by means of arresting devices acting on the bolt ends. The spacer elements are either tubularly formed, where they each envelop a bolt, or they are formed in the shape of pockets, which envelop the electrode plates; the pocket-shaped spacer elements are provided with recesses for putting the bolts through and for the admittance of liquid to the electrode plates.
In a further preferred embodiment, the support device is comb-shaped, in which case the spacer elements, as integral parts of the support device, form the teeth of the comb; in this case several such comb-like support devices are connected via a bar.
The electrode plates have a wall thickness in the range between 0.04 to 0.25 mm, where the ratio of the wall thickness to the distance of the electrodes lies in the range between 1 to 50 to 1 to 300. A wall thickness of 0.1 mm has proven to be particularly practical. The openings are evenly distributed over the electrode surface.
Contact strips are disposed laterally or at the top and bottom for improving contact, each of which is provided with a plate lug.
The comparatively simple handling has proven to be advantageous, because now a cathode exchange can take place in the form of an exchange of an entire electrode package; based on the mutual insulation of the electrode plates from each other it is possible in this case to set an optimal current density corresponding to the respective position of the electrode plate, so that all electrode plates can be removed showing a uniform degree of plating.